Such devices for electrohydraulic valve lift switching are deployed in modern internal combustion engines, to adjust the operation of the engine to the respective operating situation, so that engine power, fuel consumption or emission response can be optimized as a function of the operating situation. The aim is to reduce fuel consumption and emissions when the power requirement is low but otherwise to make maximum engine power available. An engine equipped thus is for example known from the article “Der neue Motor des Porsche 911 Turbo” (The new Porsche 911 Turbo engine”, MTZ Motortechnische Zeitung 61 (2000) 11, pages 730 to 743.
In the case of engines with electrohydraulic valve lift switching however not only is the valve lift switched but numerous engine control parameters are also changed. For an optimum effect it is of essential importance for all parameters to be coordinated in respect of each other and to be adjusted when a valve lift switch is effected. The time of the valve lift switch also has to be coordinated with the time of the other parameter changes. The problem arises here that the precise time of the valve lift switch is not known. It is known when a corresponding control signal is emitted but not the time when the valve lift switch is actually effected. One significant uncertainty factor when determining this time is the on/off valve, the switch response of which depends on temperature, oil pressure and many other influencing variables, which can in turn depend on the arrangement of the on/off valve within the engine. A precise conclusion about the switch time of the on/off valve or the occurrence of th e valve lift switch cannot therefore be obtained from the time of activation of the on-off valve. It cannot therefore be ensured that optimum coordination of the valve lift switch and other engine control parameters is achieved under all operating conditions.
It is known from the prior art that valve lift switching can be identified by means of a valve lift sensor. However this is relatively complex and expensive.